There are devices that provide an RJ-11 jack to interface POTS phones with cell phones. This would permit you to just plug your autopatch into the device. A web search will find these. They range from high end multi-line devices to those in the $100 to $200 price range.
This is a link that shows some of the lower end items. I am sure that there are more out there and there may be better ones than those shown here. This is just one of the pages I found while searching for "cellular backup for land line". http://www.thehightechstore.com/xlink_bttn.htm
